To improve the cooling effect between the stages copper is a better conductor than steel, and heavy guage copper is less prone to vibration cracking.

Paint, yes FWIW matt black radiates heat best.

agrip

10-25-2009, 08:00 PM

Some times an "unloader" rig is in those above head devices.
i.e., put pressure to unloader, the valve below is held open and the pump just chuffs air back and forth without building pressure.

This is somewhat wasteful but beats the heck out of short-cycling in high usage situations.

It does allow the motor to get a system up to speed before cutting in a load.

Hth Ag

Boucher

10-25-2009, 08:02 PM

I think you are right. The open ports were probably connected with a finned tube to cool the air as it goes from the low pressure cylinder to the high pressure. My first thoughts on the copper plumbing is that there are unloaders to hold the valves open when the pressure reaches the upper set pressure and you want to to keep the compressor turning. There would have to be a pilot valve with a regulator connected in there some where if that is what is intended. Where does the air get into the low pressure cylinder and where does the air from the high pressure cylinder connect to the receiver tank?

cuemaker

10-25-2009, 08:18 PM

Here is the back side.. yes I do have a finned tube that goes between to 2 ports...

So the finned tubed part is just to move cool air back and forth. Not just a one way pump as part of the moving air into the tank?

http://i201.photobucket.com/albums/aa129/xringx/DSCN2176.jpg

Black_Moons

10-25-2009, 09:01 PM

No. the finned tube moves air one way from the big cylinder to the smaller cylinder.
the top coppre tube is likey optional, probley more for when the cylinders are used on a gasoline motor and need a way to 'unload' (for startup and/or overpressure)

cuemaker

10-25-2009, 09:28 PM

So do I need them?

Boucher

10-25-2009, 09:54 PM

I would cap the open fitting above the intake filter. You may find that you would like to have the unloader feature. I would just deactivate it and leave it in place for now. Was there a pressure regulator and pilot valve with the compressor when you got it. Was the compressor runable when you got it?

Roy Andrews

10-25-2009, 10:37 PM

the small line from the case by the crank end is more than likely the startup unloader but could be for air powered lubrication. the top line is for continuous run and unloads at a specific pressure. the air comes in the filter on the large cylinder goes out the other side through the finned hose and into the high pressure (small) cylinder it then comes out and goes into the tank through a check valve which should be mounted directly to the tank.

Roy Andrews

10-25-2009, 10:52 PM

So do I need them?

how do you intend to run the unit? electric or gas. if gas yes you need the continuous unload feature unless your going to put the motor kill on a pressure switch. if your going electric you will need a pressure switch to control the motor or you could keep the continuous unloader and let the motor just run all the time. if your going to go to pressure switch control you need to make sure the small hose that comes out of the crank case is a start up unloader. or get a pressure switch with a startup unload feature. the way to see if the small line is an unloader is to disconnect the tube from it and then remove the brass fitting from the case. it should look like a small shraeder valve is inside the fitting (because there is). when the crank gets up to speed a weight pushes the valve closed allowing the compressor to make pressure. without the startup unloader the unit has to start against the tank pressure which is hard on the motor. if you have any other questions fire away and i will try to answer.

Axlemoron

10-27-2009, 10:46 AM

It looks to me like someone has screwed around with this. Where is the interstage cooler? A previous poster mentioned this; a tube with fins on it. Looking at the first picture, I would say the interstage cooler when on the two empty connectors there in front and did a loop around and behind the flywheel/fan.

The tube across the top looks totally wrong to me. They may have connected it where relief valves are supposed to be.

Is this an Emglo? It looks Emglo blue. If it is an Emglo, I believe there are parts diagrams available on the internet at their website.

b1vogt

11-19-2009, 09:50 PM

This is a dual output welder--450 or 300 amps. Power in required per nameplate is 56 amps @ 230 Volts (3-Phase). Is there a way to reduce this unit to a lower power ,lower input? If not I will sell it or trade for one that I can use in my shop. My available power is a 15 Hp phase converter (230V 3phase) or 100 amp 230 Volt 1-phase.

Doozer

11-19-2009, 11:25 PM

It is not an Emglo, it says Worthington on the tag. You are missing the inter-stage cooling tube. That goes behind the pulley and connects the 1st stage to the 2nd stage. The small 1/4" copper line is the crankcase breather, to the intake filter. Emglo has a similar breather line. The only thing that new copper line could be is an unloader. If there is an oil pump, oil might connect to the line and start the cylinders pumping when the unloaders see pressure.

--Doozer

cuemaker

11-20-2009, 11:10 PM

I saw that the thread got revived, so I thought I would post an update with some pics...

1st pic show the new pressure switch, safety valve and pressure gauge. On the left you see the drain...

2nd pic show the the pump painted. I dont have the fill tube connected to the check valve because the check valve required a 5/8 tube flared, so I am going to put a union from the 5/8 tube to the 1/2 tube.. wont have that till Monday. Also on top of the heads will be wired to the unloader on the pressure switch. Still need to buy the tubing for that. It will run from the big head, to the smaller head down to the pressure switch.....

Looks good. Q- Will the 1/2 tube slip into the 5/8" tube, and just solder it??
Are you gunna run a magnetic starter?

--Doozer

cuemaker

11-21-2009, 12:48 AM

Thank Doozer...

I am not sure what a magnetic starter would do for me.....care to educate me?

I never thought about soldering it... me oh my....No, i have a union on the way that does 1/2 on one end and 5/8 on the other, but a solder would make it look good.....Brilliant..

steve45

11-21-2009, 12:54 AM

It looks to me like someone has screwed around with this. Where is the interstage cooler? A previous poster mentioned this; a tube with fins on it. Looking at the first picture, I would say the interstage cooler when on the two empty connectors there in front and did a loop around and behind the flywheel/fan.

The tube across the top looks totally wrong to me. They may have connected it where relief valves are supposed to be.
Agreed, this is messed up. The output of the first stage (larger cylinder) should go through a heat exchanger (finned tube) to the INPUT of the second stage.

Believe it or not, the heat exchanger is critical to proper operation of a multi-stage compressor. In fact, it could even be unsafe in that it could cause a fire. High temperature air in a compressor with oil in the cylinders can cause ignition.

Doozer

11-21-2009, 12:55 AM

A motor starter contactor can provide overload protection when left un-attended and it makes the pressure switch contacts last way longer. I used a 24v transformer and a contactor with a 24v coil. I have a 3 way switch in my basement and one in my shop, with indicator lights. That way I can switch my air on/off from my basement and my garage. 24v makes the long switch run safer, I just used bell wire. I also wired in an octal base adjustable timer hooked to some solenoids to drain my tanks when the pressure switch cycles.

--Doozer

cuemaker

11-21-2009, 12:59 AM

Agreed, this is messed up. The output of the first stage (larger cylinder) should go through a heat exchanger (finned tube) to the INPUT of the second stage.

Believe it or not, the heat exchanger is critical to proper operation of a multi-stage compressor. In fact, it could even be unsafe in that it could cause a fire. High temperature air in a compressor with oil in the cylinders can cause ignition.

I have it, its not hooked up.. dont worry.. all is ok....

Doozer, can you suggest a product so I can read up on it?? I have a 10.6amp 1.5hp motor single phase.....